This invention relates to apparatuses and methods for forming air curtains, and more particularly to an apparatus and method specifically adapted for use with an aircraft to form an air curtain at a desired area of an aircraft such as a cargo door opening.
Air curtains are typically used in buildings having a portion which is open to the ambient environment, and where it is desirable to form a barrier to prevent the entry of airborne contaminants into the building. The air curtain is used to form a wall of air which acts as an impediment to the entry of dust, dirt and debris, as well as insects and other undesirable elements into the open area of the building. The air curtain also can help to form a temperature boundary by producing a pressure differential between the interior of the building and the outer ambient environment.
Typically, air curtains are formed by placing a plurality of high flow capacity blower systems alongside one another in an overhead orientation along the full width of the opening where the air curtain is to be formed. One such prior art blower system 200 is shown in FIG. 7. The blower system 200 includes a duct 202 within which is mounted a fan or blower 204. The fan or blower 204 is driven by an electric motor (not shown) which is also disposed within the duct 202. The blower draws air into the duct 202 and discharges it at an outlet at a suitably high velocity to form a wall or curtain 206 of air.
Blower systems such as that shown in FIG. 7 are typically quite large, heavy, noisy and bulky units and are entirely unsuitable for use with commercial or military aircraft. Furthermore, such prior art blower systems typically require a significant amount of electrical power to operate, which further makes the integration of such blower systems into an aircraft impossible or impractical.
Commercial and military aircraft nevertheless would significantly benefit if a system for forming an air curtain could be installed on the aircraft without introducing significant expense, weight, and without requiring significant modifications to the structure of the aircraft or significant electrical power to operate. The use of an air curtain would be highly desirable, for example, with cargo aircraft which have a relatively large cargo door which is opened during loading and removal of cargo from the fuselage of the aircraft. Since many such cargo aircraft are forced to operate in environments where a high degree of dust, dirt, smoke and even insects may be present, the use of an air curtain would be highly useful for preventing the entry of such elements into the fuselage of the aircraft during loading or unloading operations.
Still another important use for an air curtain would be in preventing the entry of chemical and biological warfare (CBW) airborne contaminants into a cargo bay or other interior area of an aircraft, such as during loading and unloading of a cargo compartment of the aircraft. Such a system would also help to reduce the in-flight CBW decontamination time by air purging that is presently required with military aircraft.
Accordingly, it would be highly desirable to provide an air curtain adapted specifically for use with an aircraft to provide a relatively narrow, width-wise wall of air which acts as a boundary to impede the entry of dust, dirt, smoke, insects or other airborne contaminants into an interior area of an aircraft while the interior area is exposed to the ambient environment. It would further be highly desirable to provide an air curtain adapted specifically for use with an aircraft which can be cost effectively installed on the aircraft and which does not require a plurality of heavy, high power consuming and bulky electric blower devices to be mounted within the aircraft.
Still further, it would be highly desirable to provide a system for forming an air curtain which is specifically adapted for use with an aircraft to provide a wall of air at a cargo door opening area of the aircraft to prevent the entry of dust, dirt, debris, smoke, insects and other airborne particulate matter into the fuselage of the aircraft, and where the angular orientation of the air curtain can be controllably adjusted for maximum effectiveness in forming a barrier to the entry of foreign, airborne particulate matter into the fuselage of the aircraft.
The above and other objects are provided by an apparatus and method for forming an air curtain in accordance with preferred embodiments of the present invention. The apparatus of the present invention is specifically adapted for use with an aircraft, although it will be appreciated that the system and method of the present invention will find utility in a variety of other applications, such as with transport vehicles and ground facilities, where it is impossible or undesirable to mount a plurality of heavy, bulky, high power consuming prior art blower devices in an overhead orientation to form an air curtain.
The apparatus and method of the present invention comprises at least one air intake duct which is disposed adjacent a portion of the aircraft, such as adjacent a cargo doorway formed in the fuselage of the aircraft. The air intake duct includes a fan for drawing ambient air into the duct. Preferably, a filter is also included at the intake side of the air intake duct to filter out dust, dirt, insects and other airborne contaminants. The air intake duct is coupled to a manifold which is disposed in an overhead fashion across the opening where it is desired to form an air curtain. A power unit of the aircraft is coupled via a suitable conduit to the air intake duct and includes an injector nozzle for injecting a pressurized airflow supplied by the power unit directly into the air intake duct. The pressurized airflow operates to significantly accelerate the ambient airflow delivered by the fan to produce a high pressure airflow which is directed into the manifold.
The manifold includes an outlet through which the high pressure airflow is directed to form the air curtain. In one preferred embodiment an air dispenser is secured to the outlet of the manifold. The air dispenser directs the high pressure airflow passing through the outlet of the manifold into a narrow, width-wise air stream which forms the air curtain.
The apparatus and method of the present invention thus entirely eliminates the need for overhead mounting of a plurality of large, heavy, bulky and power consuming electric blowers across the full width of the opening where the air curtain is to be formed. This significantly eases integration and implementation of the present invention into existing aircraft with a minimal degree of modifications needed to the fuselage of the aircraft.
In another preferred embodiment the manifold is mounted for rotational movement about an axis extending longitudinally along the manifold. A mechanism is included for rotating the manifold in a controlled fashion. In one preferred form this mechanism comprises an electric stepper motor. A position control system may also be included for monitoring the angular position of the manifold and controlling the stepper motor such that the manifold is rotated as needed to maintain a desired angular orientation. The ability to modify the angular orientation is desirable in those applications where, for example, the floor of the structure at which the air curtain is being directed is movable, such as when the floor comprises a loading ramp of a cargo aircraft. In such applications it is highly desirable to be able to vary the angular direction of the air curtain in accordance with the angle of the loading ramp to maintain optimum effectiveness of the air curtain in forming a barrier to the entry of airborne dust and dirt particulates, insects, etc.
In the preferred embodiment described above, the position control system is also responsive to the position of the manifold and the position of the loading ramp of a cargo aircraft which the air curtain impinges. The position control system allows the manifold to be rotated closely in accordance with the angular position of the ramp to thus maintain the air curtain at a desired angular orientation for maximum effectiveness.
In the preferred embodiment described above a flow control system is also incorporated for controlling the flow of pressurized air into the air intake duct. This enables the force of the air discharged from the manifold to be varied in accordance with a changing height of a floor which the air curtain impinges. Thus, the pressure of the air stream forming the air curtain can be varied in accordance with the distance of the manifold from a floor member such as a loading ramp.
The apparatus and method of the present invention thus forms a low cost, easy to install means for forming an air curtain specifically adapted for use with an aircraft. Advantageously, the system of the present invention makes use of a pressurized airflow provided by a power unit of the aircraft, such as an engine or an auxiliary power unit, to accelerate the ambient airflow within the air intake duct to produce a pressurized airflow within the manifold which is of suitable velocity to form an air curtain.